1. Field of the Invention
The present invention relates in general to heat exchangers for separable air conditioners and, more particularly, to a structural improvement in main bodies of such heat exchangers for miniaturizing the heat exchangers.
2. Description of the Prior Art
With reference to FIG. 1, there is shown a typical heat exchanger for a separable air conditioner. The typical heat exchanger includes an air conditioner main body designated by the numeral 1a. Mounted in back of the air conditioner main body 1a is a cross flow fan 2. Both the air conditioner main body 1a and the cross flow fan 2 are placed in the interior of a casing 1. The air conditioner main body 1a comprises a plurality of heat exchanging fins 3 of the thin plate type. A plurality of heat transfer tubes 4 penetrate and retain the heat exchanging fins 3. Generally, each heat exchanging fin 3 is made of aluminum while each heat transfer tube 4 is: constructed of copper tube having at least 7 mm diameter. In addition, the heat transfer tubes 4 generally have 9 or 10 stages and two rows, however, both the stages and the rows of the heat transfer tubes 4 may be changed in response to heat exchanging capacity of the heat exchanger. In the typical heat exchanger of FIG. 1, the number of stages of the heat transfer tubes 4 is 9 or 10, for example.
The operation of the above heat exchanger will be given hereinbelow in conjunction with FIGS. 2A and 2B.
The warm room air that was sucked into the air conditioner main body 1a through the front of the main body 1a exchanges the heat with the relatively low temperature of refrigerant flowing in the heat transfer tubes 4, thus to become cool air. The cool air in turn is discharged from the heat exchanger to the room through a grill (not shown) that is mounted on the lower section of the heat exchanger. In the heat exchanger, the refrigerant in the liquid phase is introduced into the heat transfer tubes 4 through the inlet 4a and exchanges the heat with the warm air. After the heat exchanging with the warm air, the liquid phase of the refrigerant is converted into the gas phase. The refrigerant in the gas phase in turn is discharged through the outlet 4b of the heat transfer tubes 4 so as to be introduced into a compressor (not shown). In cooling operation of the separable air conditioner, the above circulation cycle of the refrigerant is repeated.
The operation of the refrigerant flowing in the heat transfer tubes 4 of the typical heat exchanger of the separable air conditioner will be described in detail hereinbelow.
FIG. 3 is a view showing an evaporative flow of the refrigerant in a horizontal pipe section of the heat transfer tubes 4 in accordance with refrigerant flow direction.
The flow type of the refrigerant in the heat transfer tubes 4 of the heat exchanger, which heat transfer tubes 4 are mostly occupied by the horizontal tube sections, is changed in order of stratified flow annular flow.fwdarw.spray.fwdarw.annular flow.fwdarw.superheated vapor region. It has been generally noted that the heat exchanging effect of the refrigerant in the heat exchanger is best when the refrigerant shows either the annular flow type or the semi-annular flow type, which flow types cause the refrigerant to cover all over the interior walls of the heat transfer tubes 4. On the contrary, in the range of stratified flow or wavy flow, the refrigerant only fills the lower sections of the heat transfer tubes 4, so that the heat exchanging effect about the portion of stratified flow or wavy flow should be immaterial.
However, the range of both the stratified flow and the wavy flow occupies relatively large part of the stages of the heat transfer tubes 4, that is, 3 or 4 stages from the uppermost stage of the heat transfer tubes 4. In this regard, the desired miniaturization of the heat exchanger of the separable air conditioner may be achieved by reduction of the range of both the stratified flow and the wavy flow.
As described above, the typical heat exchanger for separable air conditioner is produced using the same heat transfer tubes along with the same heat exchanging fins so as to provide convenience in both designing and producing of the heat exchanger. The length of undesirable range or the range of both the stratified flow and the wavy flow should be increased, so that the heat exchanger should be large-sized.
Since the typical heat exchanger for separable air conditioner should have heat transfer tubes of 9 or 10 stages, the cost for production of heat exchanger should be increased, thus to cause the heat exchanger to be insufficiently competitive in price.